Showing posts with label AEIC. Show all posts
Showing posts with label AEIC. Show all posts

Tuesday 24 December 2019

Digital Meter vs Electromechanical Meter

Some one asked me,
Do the new digital electric meters runs faster than the old electromechanical or revolving type meter?
So let make this very clear and simple 😊,
If by faster you are implying more accurately at low currents than the answer is yes.

For example, most utilities purchase electricity meters for residential applications with a nameplate rating of 240 Volts, 2 to 200 amps, 1 phase , 3 wire, Form 2S.

These nameplate ratings would apply to both the legacy electro-mechanical “induction disc” devices or the newer solid state or digital meters.

As a former supervising technologist at a large utility meter facility, I can share with you that modern digital meters perform much more accurately at low currents than the older electro-mechanical models they have replaced.

Since there is no friction or starting torque to overcome, digital meters will respond very accurately at very low loads.

So some customers may see an increase in their kWh consumption since the old electro-mechanical meters would not respond well to electrical usage where the only devices in operation in the home ( typically in the middle of the night) drew small amounts of current. These load devices may include clock radios, cable TV boxes, cell phone chargers, etc. Digital meters will measure and record these loads accurately.

Also I can personally attest to digital meters being much more accurate in the normal operating range pf test currents applied between 5 amps to 50 amps.

From our extensive laboratory testing of meters owned by our utility and in-service meter evaluations, electro-mechanical meters have typical accuracy tolerances of +/- 0.5 % but digital meters are much more precise, typically at +/- o.2 %.

As electro-mechanical meters age some devices tend to under-respond or “slow down”. Digital meters will be accurate throughout their entire life span.

Sunday 10 November 2019

What “Neutral” Means

What “Neutral” Means

The neutral conductor is the conductor that leads back to the center tap of the utility transformer. It is connected to earth at two locations: the utility transformer and the main panel. That is why it is sometimes referred to as the grounded neutral conductor. Its designation is white or a white tape on a black cable. Neutral current is commonly referred to as return current, because once the current passes through the load, the white insulated neutral conductor makes the complete circuit back to the utility transformer. All electrical current must make a complete loop. The current starts at the utility transformer and must therefore return to the transformer; the neutral is simply the return part of that loop.
The neutral cable or wire can kill you just as readily as a “hot” cable. The same current that flows in a hot conductor flows out the neutral. If you place yourself in series within that loop, even on the neutral side, you will be electrocuted.

AC 12V-0-12V transformer